In Altman U.S. patent application Ser. No. 178,192 filed Aug. 14, 1980, now U.S. Pat. No. 4,356,157, entitled "Synthesis of Dawsonites", a method of synthesizing dawsonites [MA1(OH).sub.2 CO.sub.3 wherein M represents an alkali metal or the ammonium radical] is described, such dawsonites having utility for extinguishing fires, more particularly fires on hot metal surfaces caused by leakage of hydrocarbon fuels such as jet fuels. Such fires occur, for example, in the nacelles of jet aircraft and it is advantageous to be able to pour a powdery, solid mixture of fire extinguishing material over the hot engine surface. It is important that the fire extinguishing effect have a sufficient duration to allow time for remedial action to be taken.
It is an object of the present invention to provide improvements in dawsonites and in other aluminum compounds such as aluminum hydroxide, boehmite and alumina for such purposes.